Method for ensuring power spectrum high-and-low energy region of hydraulic machinery vibration signals

The invention relates to a method for ensuring a power spectrum high-and-low energy region of hydraulic machinery vibration signals. In a power spectrum of the hydraulic machinery vibration signals, an obvious juncture point exists between a low-frequency high energy region and a high-frequency low energy region, a variation tendency of the energy of the low-frequency high energy region and the high-frequency low energy region in the power spectrum of the hydraulic machinery vibration signals along with a vibration signal frequency is matched by adopting a piecewise function which is matched by a least squares fit, an intersection point of deviation square and the minimum piecewise function is the demarcation point of the low-frequency high energy region and the high-frequency low energy region in the power spectrum of the hydraulic machinery vibration signals.